Space between Parietal and Visceral layers. There is a little bit of fluid in the space 5-20 ml up to 50. Fluid in pericardial space keeps heart from completely filling. Can handle gradual fluid increase, but not sudden fluid onset.

The process of recharging depolarized cells back to their "ready" (polarized) state. Think of the "recovery state".

Repolarization

After cell depolarizes, the positive and negative electrical charges will again return to original positions around the cell, and the cell will prepare for another discharge. The process that follows depolarization, when cell charges are returning to their original state is called repolarization.

Absolute refractory period

occurs during depolarization and the first part of repolarization. Cardiac cells will not respond to any stimuli, no matter what

Relative refractory period

Only a stronger-than-normal stimulus can excite the heart muscle to contract. It occurs in the final stages of repolarization.

Purkinje's Fibers

rapidly spread the wave of depolarization through the ventricles.

Inherent rate of SA node

60 - 100 bpm

Inherent rate of AV node

40 - 60 Bpm

Inherent rate of Ventricles

20 - 40 bpm

Ventricular Systole

Aortic valve is open, allowing ejection of blood
Mitral valve is closed, preventing regurgitation of blood into left atrium

Ventricular Diastole

Aortic valve is closed, preventing regurgitation of blood into ventricle
Mitral valve is open, allowing blood to flow from left atrium into left ventricle.

During Diastole

Pressure in LA exceeds pressure in relaxed LV
Blood flows from LA to LV across open mitral valve
Just before the onset of ventricular systole, atrial contraction produces a slight pressure rise in both chambers (known as atrial kick).

S1 LUB

Closure of the Mitral valve.

Beginning of systole

S2 DUB

Closure of Aortic Valve

Beginning of Diastole

Contractility

ability of heart muscle to contract in response to electrical stimulation.

Cardiac output

adult cardiac output

amount of blood pumped by the LV in 1 minute.

between 3 - 8/L per minute

Cardiac index

Normal CI =

Cardiac output divided by the body surface area. It describes the CO in terms of liters per minute per square meter of body surface area.

2.5 - 4/L/Min/M^2

S3

Rapid Ventricular filling.
Occurs during Diastole.

S4

marks atrial contraction and immediately precedes S1 of the next beat. Ventricle us unable to take the last push of blood from atrium. Atrial has to work harder to get fluid into ventricle. May indicate hypertrophy, disease or injury of the ventricular wall.